Population growth and urban development may impact the health of coral reefs. Development activities may cause erosion resulting in the runoff of sediments which eventually reach the coral reefs. Storm water runoff may carry fertilizers into the ocean causing damage to the coral reefs, and an increase of nutrient concentrations in the reef may cause an increase of algae which may smother the corals. Sizable foreign objects such as sunken boats and planes provide rich micro-sanctuaries for a plethora of sea life that otherwise would not exist.
The harvest of resources from the sea is ever growing. Overfishing has changed the ecological dynamics of marine communities allowing some organisms to dominate reefs that were once controlled by large reef fish populations.
Tourism dollars help to fund scientific research and environmental remediation activities. Tourism may contribute to reef damage. Divers and snorkelers may harm the corals by touching the polyps, and boats transporting tourists to the reef may damage it by dragging anchors.